Dividing marble slabs.



J. PBIRCE. DIVIDING MARBLE SLABS.

. APPLIOATION FILED JUNE 13 Patnted Mar. 2, 1909.

a sHEE'TssHEET 1.

INVHW OR 2- .WITNESSES:

J. RpPEIRCE.

DIVIDING MARBLE SLABS. APPLIOATION FILED JUNE13,1907.

Patented Mar.2,1909.

3 SHEETS-SHEET 2.

INVENTOR X44 2 Mk Alto/721% J. R. PEIRGE.=

'DIVIDIN G MARBLE SLABS' APPLICATION- FILED JUNI 113, 1907. v

Patented Main 2, 1909.

'3 SHEETS-SHEET a.

. Y. m M A 7 l/ WITNESSES:

UNITED STATES PATENT OFFICE.

JOHN ROYDEN PEIRGE, OF NEW YORK, N. Y., ASSIGNOR TO ROYDEN MARBLEMACHINERY- COMPANY, OF NEW YORK, N. Y., A. CORPORATION OF NEW JERSEY.

DIVIDING MARBLE SLABS.

Specification of Letters Patent.

Patented March 2, 1909.

Application filed June13, 1907. Serial No. 313,741.

analogous to the operation ,of a steel circularsaw with fixed teethcutting through a hard wood plank. For this purpose a rapidly revolvingthin wheel of carborundum agglom erated with a firm (preferably avitrified) bond is used, the sharp particles of which act like the fixedteeth of a steel saw instead of being easily torn out of their matrixand acting as a loose sharp abradant. The bond is so hard. and strong asto facilitate the making of the wheel of minimum thickness. Thispossibility of using a very thin wheel not only cheapens the wheel andinsures the removal of a com aratively insignificant quantity of marble,ut also calls for the expenditure of a minimum amount of power to driveit, and permits the wheel to be forced through the marble at a highspeed for a given power. Notwithstanding its thinness, the wheel cannotbe substantially deflected by the usually oblique irregularities of themarble even when forced through the marble at a rapid rate, and willmake a straight out at comparatively high speed without stunning themarble or breaking the wheel. The rapid revolution of the carborundumwheel introduces a gyroscopic effect which immensely strengthens itsresistance to lateral deflection, and permits the use of a wheel so thin(fivesixteenths 5/16 of an inch or less) in practice for wheels of 10,12 or 14 inches diametcrthat it would be easily broken by a slightpressure when at rest. Such wheels, however, when in rotation, withstanda series of lateral blows or pressures such as are necessarilyencountcrcdby reason of the lack of homogcncity of the marble, and thenecessary imperfections of even the best machinery. The bonding of theparticles so that they act as has. teeth instead of as a loose abradant,makes the wheel durably effective, the particles not being torn fromtheir matrix before they have done approximately all the work which theyare capable of doing, and have become so dulled that they arepractically worthless.

The particular field of usefulness of the invention, namely, thedividing of comparatively thin slabs, makes possible the use of wheelsof the smallest diameter and consequently of the highest efficiency andthe greatest thinness. The diameter is neces-. sarily limitedby theimpossibility of molding inte rally of large diameter, a wheel whichshall be so thin. as to satisfy the commercial 4 requirements of lowinitial ex ense, low consumption of power and smal waste of marble, andthe techincal requirement of sufficient lateral strength to reventdeflection. Concerning the possibility of deflection, I have observedthat the use of wheels with a soft; bond operating at commerciallypossible speeds, results in the cutting of a ine which is far fromstraight, and which would not be accepted by builders for the edges ofwall facing slabs or the like. As such a wheel runs into an extra hardportion of the marble at a good speed, it is materially deflected out ofa straight line; and it would require impracticably slow and carefulfeeding to be worked through the'marble in a substantially straightline, as well as resulting in a less sharp edge on the marble. Theinvention is also restricted to the use of a wheel of the materials andstructure described.

Marble cutby this process is left with a clean sharp edge and a perfectarris. There is' little or no subsequent rubbing or polishing of theedge, such as is always necessary with An additional feature of greatimportancev is the flaring of the edge of the carborundum wheel. I havefound that such flaring reduces the number of breakages of the copingwheels to a negligible point, whereas without such flaring the wheelsare in danger of breaking more or less often. The exact reasonWhyflaring 0f the edge should reduce the tendency of the wheel to breakis not clear, especially as the flaring wheels used have their greatestthickness, their thickness at lofi the edge, no greater than thethickness of the flat wheels, and the material removed from the flarededge inward to the hub would panying drawings of apparatus for carry ngout the process of the invention.

seem to lessen their capability of resisting lateral pressures.Nevertheless the differpnce in this respect is clear and very much inavor of the flared wheels.

Further advantages in detail are referred to hereinafter in connectionwith the accom- Figures 1, 2 and. 3 are respectively a plan, side elevaton, and. cross section of an apparatus in whichthe cutting wheel ismounted underneath the slab; Fig. 4 is an enlarged detail incross-section of the same machine; Fig. 5 is a longitudinal section ofanother type of machine in which the Wheel is mounted above the slab;Fig. 6 is an enlarged d'e-- tail in cross-section of the same. I

Referring to the embodiment of the invention illustrated, the marbleslab A may be mounted upon a movable bed B having a slotted centerthrough which projects upand need not be here described in further dotail. The wheel C in each case is carried upon a comparatively smallshaft rotated rapidly in antifriction bearings, so as to secure maximumspeed without the necessity for high pressure such as necessarilyaccompanics the use of'steel tools on marble. The wheels for example maybe rotated at about 2,000 revolutions per minute, or a peripheral s eedof approximately a mile a minute.

i he wheels are preferably of 10, 12 or 14 inches diameter, the smallestdiameter being the most efficient. As the diameter of the wheel isincreased the area of contact with the marble increases, and the totalpressure on the wheel necessary to secure a given unit pressure betweenthe wheel and the marble, or to secure the desired penetration of thecutting edges into the marble, increases; and at the same time thelateral strength of the wheel to resist'such total pressure, decreasesas its diameter is increased. The maximum thickness of the wheels whichI use is about a half inch. For most work, wheels of fivesixteenths(5/16) of an inch in thickness will stand the strain satisfactorily, andin especially light work 1 have even used wheels of one-quarter of aninch in' thickness with success. The rate of feed of the .wheel longitu-'dinall throughthe marble varies between wide 'mits byreason ofthe widevariations in the hardness and degree of uniformity en countered inmarbles, and from other causes. Thejmachineswhich I have used aredesigned for speeds from six inches to: thirtys1x inches a mmute, andthis range will cover most of the .cases arising in practice.

The material of the wheels is carborundum of a degree of coarsenessdepending upon various conditions. An increase in the coarseness pfthegrain increases up to a certain point the rapidity of cutting. On theother andthe grain must be so me as to permit of the molding of thewheel with a number of grains across 'its thickness, and this, with thethin wheels which are essential to success, restricts the size of thegrains. Furthermore the finer grains have a supplementary advantage ileaving a better edge andarris than the coarser grains. I prefer formost classes of work to useapproxunately 10-grit or IO-mesh carborundum,that is to say carborundumwhose grains will pass through a sieve of 10meshes tothe linear inch.

The wheels are formed by molding them in the usual way with a bond whichmust hold the particles of carborundum so firml that they out like thefixed teeth of the ord Iia steel saws used in sawing hard wood, aredurabl efficient, so that they do substantially al their work whilebound in to the Wheel. -This is very important in connection with thedividing of thin slabs, because after the particles are once torn outfrom their matrix, they can-remain in operative position, that isbetween the wheel and the marble, for only the briefest moment of time.In common stone sawing machines where-a steel or other flat non-toothedblade revolves or reci roe-ates in the groove in a thick stone blocwhile a loose abradant is fed into the same groove with water, theabradant is held in cutting position between the blade and the stone fora substantial period of time; furthermore with such rooesses it iscustomary only to use abrat ants which become dulled much more ra idlythan carborundum, sinceit is impossib le to assure the abradants beingin the operative osition for a period of such length as would enecessary to utilize all the cutting power of carborundum. But fordividing slabs inthe manner contemplated by" the iresent invention, itis important to carry "the cutting particles lof carborundum within thematrix of the wheel during their-life so to J' speak that is to say,during the entire pfirio'd during which they are -0iliciently s a1 Tl iebond is not only "such as to hold the teeth firmly,-but it is itselfhard and strong, so that notwitlistandin the thinness of the wheel itcannot be su stantially deflected. In Fig. 1 there is indicated indotted lines a portion G such as frequently occurs in marble, and whichmay be materially harder than the rest of the slab. The wheel may strikethis hard portion'G at a ver slight angle, so that the tendency" to deset the wheel will be very great. Nevertheless the bond must be so hardand strong'as to prevent anydefiection which will be noticeable to theeye, otherwise the slab could not be laid on a wall with joints of theperfection which are demanded in practice. Furthermore such hard spacesG in the marble tend to break the wheel, but my experiments have shownthat by the use of a hard bond, such foi' example as a vitrified bond,and by reason of the added strength due to the gyrosco ic action of therapidly revolving wheel, may employ wheels of the dimensions stated inpractically all classes of work.

In my efforts to provide an o erative machine with the very thin whee swhich are essential to commercial success, I have found that with thinwheels of the style in the market (and previously used only forsharpening small tools and similar work), that is, having flat faces,the number of breakages in a Weeks running of the machine amounted to asubstantial item of expense, this disadvantage however beinginsufficient to overcome the technical and commercial advantages ofusing a thin wheel. I have, however, succeeded in practicallyeliminating this disadvantage also by dishing the faces ofthe Wheelsslightly, so that their edges flare as indicated in Figs. l and 6. Thisfeature of construction while removing the last obstacle to commercialsi'iccess of the wheels, adds practically nothing to their cost. In theordinary manufacture of the wheels they are molded and then baked,

and theirfaces are afterward dressed to a plane. The dressing of thefaces to the dished shape shown is no more expensive than the dressingof them to a flat surface, it being necessary only to feed the dresserprogressively deeper into the face of the wheel as it moves toward thecenter thereof.

This feature of construction is claimed in a prior application forpatent No. 260,792, led May 17, 1905, independently of thequalifications of the present invention. 3

For keeping marble as cool as possible and reducing the friction of thewheel, it is preferable to employ jets of water projected upon the edgeand side faces of the wheel. Preferably the bond used is so hard thatparticles of carborundum cannot be torn out 'tiall which consists incutting through it with a wheel of carboruno um rotating rapidly withslight pressure, said wheel having a diameter of approximately twelveinches, and being agglomerated with such a firm vitrified bond that thesharp particles out like fixed teeth, and the bond being so hard andstrong that notwithstanding the thinness of the wheel it cannot besubstantially deflected by the oblique irregularities of the marblewhile operating with a rapid feed, said wheel being approximatelyfive-sixteenths of an inch thick at its edge and having its side. facesdished.

2. The process of dividing a marble slab which consists in cuttingthrough it with a rapidly rotating wheel of carborundum, said wheelhaving a maximum thickness of not more than approximately half an inch,and being agglomerated with such a firm bond that the sharp particlescut like fixed teeth, and the bond being so hard and strong thatnotwithstanding the thinness of the wheel it-cannot be substantiallydeflected by the oblique irregularities of the marble while operatingwith a rapid feed.

3. The process of dividing a marble slab which consists in cuttingthrough it with a rapidly revolving thin wheel composed of carborundumagglomerated with such a firm bond that the sharp particles out likefixed teeth, and the bond being so hard and strong that the wheelnotwithstanding its thinness cannot be substantially deflected by theoblique irregularities of the marble while operating with a rapid feed.

'4. An apparatus for dividing a marble slab including a wheel composedof carborunslight pressure and for moving it through theslab, said wheelhaving a diameter of approximately twelve inches, and being agglomeratedwith such a firm vitrified bond that the sharp particles out like fixedteeth,

and the bond being so hard and strong that I the wheel notwithstandingits thinness cannot be substantially deflected by the obliqueirregr-ilaritics of the marble while operatlng with a rapid feed, saidwheel being a proxi- 1 mately five-sixteenths of an inch thic at itsedge and having its side faces dished.

5. An apparatus for dividing a marble slab including a wheel composed ofcarborundum, and means for rotating it rapidly and for moving it throughthe slab, said wheel having a maximum thickness of approxi- 'matcly halfan inch, and being agglomerated with such a firm bond that the sharpparticles out like fixed teeth, the bond being so hard and strong-thatnotwithstanding the thinness of the wheel it cannot be substandeflcctedby the oblique irregularities pf t c marble while operating with a rapideed.

4"" I I ,914,3o3

6. An avparatus for dividing a marble {by the oblique irregularities ofthe marble 1Q slab inclu ing a thin Wheel composed of while operatingWitharapid feed. carborundum, and means for rotating it In witnesswhereof, I have hereunto rapidly and for moving it through the slab,signed my name in the presence of two subthe carborundum beingagglomerated with I scribing witnesses.

sucha firm bond that the sharp particles cut JOHN R0 YDEN PEl R CE. likefixed teeth, the bond being so hard and Vl-"itnesses: 1 V 1 strong thatthe Wheel notwithstanding its 5 l)()MINGO A. USINA,

thinness cannot be substantially deflected I THEODORE T. SNELL.

